Biology Reference
In-Depth Information
developed in the modern sense, but it is similar and for future reference
may be broadly defi ned as follows:
MAT of the coldest month does not fall below about 18°C, generally above
25°C; no pronounced or extended dry season; broad-leaved, evergreen, drip
tips, lianas, and buttressing common; leaves mostly mesophylls (megaphylls
in the substratum); entire-margined leaves at least 75 percent.
In eastern North America, the Cretaceous vegetation of the Appalachian
uplands is not well known, but it was likely a notophyllous broad-leaved
evergreen forest with some deciduous elements. Representatives are found
along the Atlantic Coastal Plain as remarkably well-preserved fossil fl owers
in the Raritan Formation of New Jersey (Turonian in age; 90.4-88.5 Ma).
They include the Clusiaceae (fi g. 5.2), Ericaceae, Iteaceae (Saxifragaceae;
Hermsen et al. 2003), Magnoliidae, and others (Crepet and Nixon 1994,
1998; Crepet et al. 1992; Nixon and Crepet 1993). In the Mississippi Em-
bayment region of Tennessee, leaves in the Late Cretaceous McNairy Sand
and associated fl oras are 62 percent to more than 70 percent entire mar-
gined, growth rings are poorly developed, and drip tips are rare. Leaves are
small and somewhat coriaceous (thick) for a typical tropical rain forest,
Figure 5.2
Flower of
Paleoclusia
(Clusiaceae) from the Late Cretaceous
(Turonian) of New Jersey. Pistil with
broken carpel wall and numerous ovules.
From Crepet and Nixon 1998. Used with
permission from the Botanical Society of
America, St. Louis.
